发明名称 |
Digital composite tone alerting. |
摘要 |
<p>Within a digital PBX system or the like, an apparatus permits provision of digital composite tone alerting particularly suitable for piezoelectric transducers with one arbitrarily selectable tone, by means of logic circuits for latching the sign-bit in a received PCM signal that exceeds a validity threshold, and by combining the toggling sign-bit with another tone to yield the composite tone.</p> |
申请公布号 |
EP0331371(A2) |
申请公布日期 |
1989.09.06 |
申请号 |
EP19890301858 |
申请日期 |
1989.02.24 |
申请人 |
NORTHERN TELECOM LIMITED |
发明人 |
QUESNEL, GUY CHARLES;LYNCH, DAVID LAWRENCE |
分类号 |
H04M19/02;H04B14/04;H04M19/04;H04Q1/448;H04Q1/45;H04Q1/457 |
主分类号 |
H04M19/02 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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